Loads from electrical equipment that is mounted due to environmental issues have been increasing rapidly in recent years, and further increases in generated power are being sought from Lundell rotors. If attempts are made to answer these demands within the scope of conventional design, the alternators are invariably increased in size, which is undesirable since the weight of and space occupied by such alternators is increased. Increases in alternator size are also known to give rise to new problems such as increased rotor inertia, and engine speed fluctuations and alternator inertial torque interacting and generating belt vibration and slippage. Because of these facts, there is demand to increase alternator capacity, that is, reducing alternator size and increasing output, without increasing alternator main body size.
In consideration of these conditions, first conventional alternators have been proposed in which permanent magnets are disposed between circumferentially adjacent claw-shaped magnetic pole portions of a Lundell rotor (see Patent Literature 1, for example).
Second conventional alternators have also been proposed in which permanent magnets are disposed on mounting faces of peripheral edges of magnetic pole pieces (corresponding to yoke portions) that are positioned between magnetic pole fingers (corresponding to claw-shaped magnetic pole portions), and straps are disposed so as to cover the permanent magnets and are fixed to the magnetic pole pieces by nails (see Patent Literature 2, for example).
Patent Literature 1: Japanese Patent Laid-Open No. SHO 61-85045 (Gazette)
Patent Literature 2: Japanese Patent Laid-Open No. 2004-153994 (Gazette)